<!DOCTYPE html>
<html lang="zh-cn">
    <head>
        <meta charset="UTF-8"/>
        <meta name="viewport" content="width=device-width, user-scalable=no, initial-scale=1.0, maximum-scale=1.0, minimum-scale=1.0" />
        <meta http-equiv="X-UA-Compatible" content="IE=edge,chrome=1" />
        <title>小图标与文字垂直居中对齐</title>
        <style>
            *{padding:0;margin:0;}
            .close-btn{background:red;color:#fff;height:45px;width:120px;border-radius:5px;text-align:center;position: relative}
            .img-responsive , .close{position: absolute; top:50%; transform: translate(0, -50%);}
            .close { margin-left: 30px}
        </style>
    </head>
    <body>
        <div class="close-btn">
            <div class="img-responsive">
                <img src="http://s1.mi.com/m/images/20151028/top-x.png">
            </div>
            <div class="close">关闭</div>
        </div>
    </body>
</html>